1961 film
- Actor-Inspired Element: Vincent Price suggested Nicholas say that the pendulum "must be kept in a constant state of repair" and "that cannot be stopped" when Francis first arrives at the castle.
- Awesome, Dear Boy: John Kerr did the film just to work with Vincent Price.
- Creator Backlash: John Kerr regrets his performance in the final scene."He just wanted me to be dazed ... and then get off! And I did. So I don't think I did that moment very well."
- Enforced Method Acting: John Kerr was genuinely nervous for the scene where Francis is strapped to the torture device.
- Fake Nationality: American actors playing Spanish and English characters, though Not Even Bothering with the Accent. Ironically Barbara Steele - who plays Elizabeth - was English. But Roger Corman felt her working class accent didn't fit, and so she was dubbed by an American woman.
- Follow the Leader: Roger Corman had made a successful film of The House of Usher, also adapted from an Edgar Allen Poe work. According to Word of God the studio wanted "another film with a Poe title attached to it."
- No Budget: The film was only made for $1 million. To put it in perspective, that was the entire salary for Elizabeth Taylor on the expensive epic Cleopatra that same year.
- One-Take Wonder: The climactic scene of Nicholas strangling Elizabeth was all done in one take.
- Playing Against Type: John Kerr was best known for his roles in South Pacific and Tea and Sympathy. A Gothic Horror period piece was quite different for him.
- Playing with Character Type: Vincent Price normally plays hammy villains, but most of the movie is spent in doubt over whether he is the villain. It turns out he's not, but Sanity Slippage turns him into one anyway.
- Production Posse: Luana Anders would make two more films with Roger Corman - The Young Racers and The Trip (1967). Antony Carbone (Dr Leon) had made three films with Roger Corman prior to this one.
- Prop Recycling: Most of the props and sets were scrounged from other productions due to the low budget.
- Throw It In!: When the film was sold for TV, they needed to pad out the running time. Roger Corman got Luana Anders - the only available cast member - and shot a scene that was tacked onto the opening. It featured Catherine in a madhouse and the movie would then take place as a flashback story.
- What Could Have Been:
- Roger Corman had intended to adapt The Masque of the Red Death - also by Edgar Allen Poe. But he was worried it was too similar to Ingmar Bergman's The Seventh Seal - and filming that would also require a dance troupe that the studio couldn't afford. He would later do an adaptation three years down the line.
- The screenplay had a scene with a Happy Flashback of Nicholas and Elizabeth horseback riding, but it was never filmed because Richard Matheson felt showing them outside the castle in broad daylight would kill the mood.
- There were some last words for Nicholas as he lies dying in the pit - saying "Elizabeth, what have I done to you" - and it would then cut to Elizabeth in the Iron Maiden. Roger Corman cut this because he felt the film should remain visual at that point.
